How do I classify an image that contains only polygons?
To make it easy take small known CNN network like Alex Net, train like : input  is image, output is [1,0,0,] separate, [0,1,0], encloses, [0,0,1] overlap. Cause you task is easy i guess that will be fine. But it can be done without ML just analysing image with constant algorithm by where are the points of poligons.